What’s the weirdest thing you learned this week? Well, whatever it is, we promise you’ll have an even weirder answer if you listen to PopSci’s hit podcast. The Weirdest Thing I Learned This Week hits Spotify, YouTube, Apple, and everywhere else you listen to podcasts every-other Wednesday morning. It’s your new favorite source for the strangest science-adjacent facts, figures, and Wikipedia spirals the editors of Popular Science can muster. If you like the stories in this post, we guarantee you’ll love the show.
FACT: Hector the tickle robot is real, and they’re spectacular
By Rachel Feltman
Have you ever wondered why humans are so ticklish? While many animals experience a type of tickle known as knismesis—a sort of moving itch caused by motion against your skin—the laugh-out-loud sensation called gargalesis is way less common. It’s a phenomenon that’s pretty unique to primates (though it’s possible that rats are a bit ticklish as well). And while there are plenty of theories, no one has a great explanation for why this ticklishness evolved—or at least not one that would be easy to confirm.
But while the origins and purposes of gargalesis remain mysterious, that hasn’t stopped scientists from studying how tickling works. In one recent study scientists surveyed adults from several distinct cultures to see how they felt about tickling. The results were surprisingly universal. Participants from The Netherlands, Greece and China gave comparable answers about their history of tickling and being tickled and reported being ticklish in the same locations. That hints at a deep evolutionary origin for this sensation (and our feelings about it).
This most recent study relied on survey data, but other research projects have tried to take a more quantitative look at tickles. That’s where Hector the tickle robot comes in. He’s designed to deliver a perfectly-calibrated foot tickle on command, allowing scientists to track exactly what physiological changes occur post-tickle and exactly when they kick in. He’s also helping scientists understand why we can’t tickle ourselves—and how that can help us survive unwanted tickling from others. Listen to this week’s episode to learn more!
FACT: How prickly ash and chili pepper combine to create a fascinating taste explosion
Featuring Priya Mani
This week’s episode features special guest Priya Mani. She’s a food historian, award-winning writer, and a designer who leads research-driven projects on ingredients and flavor. She joined us this week to share some facts from her upcoming book, “Spiced: Recipes Celebrating Spices from Around the World.” You can preorder it now!
Priya took us on a historical, culinary and scientific journey to explain why sichuan peppercorns (and other berries from various species of prickly ash) make your mouth buzz instead of burn. It all comes down to a compound called sanshool.
When you eat food that’s spicy—think a hot chili pepper—the compound called capsaicin binds to the same receptors in your skin that are stimulated by actual heat. WHen these TRPV1 receptors get activated, they signal to your brain that something dangerously hot is touching you.
You might associate szechuan peppercorns and other kinds of prickly ash berries with spicy food, but these fruits don’t actually contain any of the aforementioned capsaicin—so they don’t trick your brain into sensing heat. Sanshool can trick your brain in an entirely different way by acting on potassium channels, which are tiny pores that let potassium flow out of your nerve cells. By giving positively-charged potassium ions an easy exit, nerve cells are able to maintain a slightly-negative charge that keeps them from randomly firing.
Sanshool manages to block one of those potassium channels, which means positive charge starts to build and the nerve cell gets closer and closer to firing. The result is a hyperactive neuron that starts stuttering out little bursts of irregular signals. Your brain does the best it can to interpret that information, and the result is a sense that something is literally buzzing inside your mouth.
That’s why dishes that combine prickly ash berries with chili peppers are infamous for creating a culinary sensation like no other: your brain is basically telling you that there’s a hot bee bouncing around your mouth. And gosh, that fiery insect is delicious.
You can find more of Priya’s fantastic food science on Instagram.
FACT: These shark have teeth in their eyeballs
By Laura Baisas, News Editor and co-host of Popular Science’s Ask Us Anything podcast
While interviewing marine biologist, Jaida Elcock (@sofishtication_) an MIT and Woods Hole Oceanographic Institution (WHOI) PhD candidate and ace whale shark-tagger, she told me that whale sharks have teeth on their eyeballs. This sounded insanely painful to me, so I had to know more.
Whale sharks (Rhincodon typus) are the biggest fish in the world. While their maximum size is still a mystery, they can grow as large as 60 feet and weigh about 11 tons. In addition to that girth, they really do have tiny teeth covering their eyeballs called dermal denticles. Dermal denticles themselves are found on several shark species and they cover their bodies like scales. They are small, V-shaped pieces and decrease drag and turbulence as they swim. While dermal denticles do help sharks swim faster, they also provide some defence against any other sharks that might try to take a bite of them
The dermal denticles on whale shark’s eyeballs, also called eye-teeth, likely help shield their eyes from the elements. A team in Japan first detailed this in a study published in 2020 in the journal PLOS One. They studied the eyes of both living and dead whale sharks and saw that a single whale shark eyeball could have over 3,000 dermal denticles around the eyes. They are also clustered around the iris.
Most sharks have poor eyesight, so much protection around their eyeballs means that their eyesight is likely pretty important for whale sharks. Evolution is cool.
The post Yes, scientists really built a “tickle robot.” Here’s why. appeared first on Popular Science.